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Heading into Autumn Equinox, Vitamin D is Top of Mind (Again)

By Michael McBurney

Have all the vitamin D researchers been on vacation? Who would believe that it has been almost a month since our last blog on vitamin D? Today’s blog highlights a new scientific report on the role of vitamin D in older adults. Takehome message: “Plasma 25(OH)D concentrations predict subsequent lower 13-y total mortality and incident cardiovascular disease, respiratory disease, and fractures.”

To be clear, despite the quote above, Khaw and colleagues are reporting a correlation not causal evidence. Serum (not plasma) samples were collected from 14,641 men and women (42-82 y, mostly white residents of Norfolk, UK in 1997-2000. [Wonder how the yes/no referendum is going? Is it still correct to refer to the United Kingdom?]. All volunteers were followed up (an average of 13y later) for health events. Total 25(OH)D concentrations were categorized into 5 groups: <30, 30 to <50, 50 to <70, 70 to <90 and ≥90 nmol/L. Mean 25(OH)D3 and 25(OH)D2 concentrations were 56.2 and 0.35 nmol/L, respectively. The differential in the respective blood levels is probably explained by the fact that less vitamin D2 (ergocalciferol) is consumed and ergocalciferol is not equivalent to cholecalciferol in maintaining vitamin D levels.

The most important insight is the dramatic change in relative risk (deaths) from respiratory disease and fractures with serum vitamin D concentration. It is not surprising that one of the first vitamin D – health outcomes reported was trunk muscle strength and body sway which is associated with the risk of falls and fractures.